1. Field of the Invention
The present invention relates to three-dimensional object preview devices, three-dimensional printing apparatuses, and three-dimensional object preview methods.
2. Description of the Related Art
A three-dimensional object is formed, as is known in the art, using three-dimensional data representing a shape of the three-dimensional object. Such a technique is disclosed in JP 02-130132 A, for example.
A three-dimensional printing apparatus disclosed in JP 02-130132 A includes a discharge nozzle from which liquid photo-curable resin is discharged. This discharge nozzle is movable along X, Y, and Z axes of an XYZ rectangular coordinate system. The photo-curable resin discharged from the discharge nozzle is exposed to light. The photo-curable resin exposed to light is cured to form cured layers. These cured layers are stacked one on top of another, thus forming a three-dimensional object.
Such cured layers are formed in accordance with cross-sectional image data. The term “cross-sectional image data” refers to data representing a cross-sectional shape obtained by dividing a three-dimensional object at a predetermined interval along the Z-axis. Note that cross-sectional image data represents a cross-sectional shape parallel to an XY plane. A plurality of pieces of cross-sectional image data are generated from a single piece of three-dimensional data representing a shape of a three-dimensional object.
A three-dimensional object can partially deform under its own weight while being formed. To prevent such deformation and accurately form a three-dimensional object, a support structure arranged to support the target object is three-dimensionally printed in some cases for a three-dimensional object (hereinafter referred to as a “target object”). Such a support structure will hereinafter be referred to as a “support object”. A combination of a target object and a support object will hereinafter be referred to as a “full object”. FIG. 6 illustrates an example of a target model TM serving as a three-dimensional model for a target object, an example of a support model SM serving as a three-dimensional model for a support object, and an example of a full model FM serving as a three-dimensional model for a full object.
A three-dimensional object is formed using a three-dimensional printing apparatus as follows. First, three-dimensional data of a full object is generated using three-dimensional data of a target object and data of a support object which supports the target object during forming the three-dimensional object. Then, a computation is performed to generate a plurality of pieces of cross-sectional image data from the three-dimensional data of the full object. If the target object has a complicated shape, an error or miscomputation, for example, can occur during the computation, resulting in a defect in the generated cross-sectional image data, e.g., a partial loss of the cross-sectional image data.
Unfortunately, there is no method known in the art that enables an operator to determine a defect in cross-sectional image data before actually starting to form a three-dimensional object. The only way known in the art to determine a defect in cross-sectional image data is to observe a three-dimensional object that has ended up being formed unsuccessfully. Consequently, an operator has to correct defective cross-sectional image data after a three-dimensional object has actually been formed, which means that such a correction has to be made repeatedly each time a three-dimensional object is formed.
A three-dimensional object is formed by stacked cured layers, and thus has steps between the cured layers adjacent to each other. When such steps are small, a three-dimensional object has a smooth surface, but when such steps are large, a three-dimensional object has a rough surface. Unfortunately, no technique known in the art allows an operator to find how smooth the surface of a three-dimensional object is until the three-dimensional object is actually formed. Thus, in some cases, the surface of a three-dimensional object, which has actually been formed, is not as smooth as an operator has expected.
For example, the surface of a three-dimensional object may be satisfactorily smoothed by reducing thicknesses of cured layers. This, however, makes forming of the three-dimensional object time-consuming. To overcome such a problem, thicknesses of cured layers are preferably determined so as to minimize the time required to form a three-dimensional object while keeping a surface of the three-dimensional object smooth enough to satisfy a required smoothness level of the three-dimensional object.
A useful solution is to use cross-sectional image data so as to enable an operator to preview an actual image of a three-dimensional model that represents a shape of a three-dimensional object which is going to be actually formed. Such a solution enables the operator to, for example, adjust thicknesses of cured layers, which affect the surface smoothness of the three-dimensional object, or correct defective cross-sectional image data while observing the formed image of the three-dimensional model in advance. Consequently, the three-dimensional object is easily formed as desired.